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Gases are compressible.Gases fill any container that they occupy.
Gases expand in the heat.Gases do not settle in their container.
KINETIC MOLECULAR THEORY OF GASES
A gas consists of very small particles. The particles are in constant, random, straight-line motion.
The molecules of a gas are very far from each other relative to their size.
There is no interaction between molecules, they act independently of each other.
Molecules collide with each other and with the walls of the container in a perfectly elastic manner.
COMMON UNITS OF PRESSURE
Units Symbol Equivalent to 1 atm
Atmosphere atm 1 atm
Millimeter of Mercury
mmHg 760 mmHg
Torr Torr 760 Torr
Pascal Pa 101326 Pa
Kilopascal kPa* 101.326 kPa
Bar bar 1.01325 bar
Millibar mb 1013.25 mb
Pounds per square inch
psi 14.7 psi
Boyle’s Law
Gay- Lussac’s
Law
Dalton’s Law of Partial
PressureCharles’
LawAvogadro’s
LawGrahams Law of Effusion
Combined Gas Law
Ideal Gas Law
A TANK OF NITROGEN HAS A VOLUME OF 14.0 L AND A PRESSURE OF 760 MM HG. FIND THE VOLUME OF THE NITROGEN WHEN ITS PRESSURE IS CHANGED TO 400 MM HG WHILE THE TEMPERATURE IS HELD CONSTANT.
Given:V1 = 14 L
P1 = 760 mm Hg
P2 = 400 mm Hg
V2 = ?
Equation:P1V1 = P2V2
V2 = P1V1
P2
V2 = 760 mm Hg(14 L)
400 mm Hg
V2 = 26.6 L
A BALLOON HAS A VOLUME OF 2500 ML ON A DAY WHEN THE TEMPERATURE IS 30 0C. IF THE TEMPERATURE AT NIGHT FALLS TO 10 0C, WHAT WILL BE THE VOLUME OF THE BALLOON IF THE PRESSURE REMAINS CONSTANT?Given:T1 = 30 0C = 303 K
T2 = 10 0C = 283 K
V1 = 2500 ml
V2 = ?
Equation:V1 = V2
T1 = T2
V2 = V1T2
T1
V2 = (2500 ml)(283K)
303 K
V2 = 2, 335 mL
COMBINED GAS LAW
= describes the relationship among the pressure, volume and
temperature at a constant amount of gas
= Boyle’s Law and Charles’ Law
COMBINED GAS LAW
Boyle’s LawP ά 1/V
P1V1 = P2V2
Charles’ LawV ά T
V1/T1 = V2/T2
V ά T/P
P1V1 = P2V2
T1 T2
Constant: n
A GIVEN MASS OF GAS HAS A VOLUME OF 800 ML AT -23 0C AND 300 TORR. WHAT WOULD BE THE VOLUME OF THE GAS AT 27 0C AND 600 TORR OF PRESSURE? THE AMOUNT OF GAS S CONSTANT.Given:V1 = 800 mLT1= -23 0C = 250 KP1 = 300 torrT2 = 27 0C = 300 KP2 = 600 torrV2 = ?
P1V1 = P2V2
T1 T2
V2 = P1V1T2
P2T1 V2 =(300 torr)(800 mL)(300 K) (600 torr)(250 K)
V2 = 480 mL
APPLICATIONS OF COMBINED GAS LAW
This law gives us an insight on how gases and volatile liquids should be stored.
Gas tanks containing LPG inside the container should be stored in cool places to prevent the build-up of a high pressure esp. if the gas is flammable.
A 2 L FLASKS CONTAINS HELIUM GAS AT A PRESSURE OF 685 TORR AND A TEMPERATURE OF 0 0C. WHAT WOULD BE THE PRESSURE IN THE FLASK IF THE TEMPERATURE IS INCREASED TO 150 0C?Given:P1 = 685 torrT1 = 0 0C = 273 KT2 = 150 0C = 423 KP2 = ?Equation:
P1 = P2
T1 T2
P2 = P1T2
T1
P2 = (685 torr)(423 K) 273 K
P2 = 1, 061 torr
IF 0.25 MOL OF ARGON GAS OCCUPIES A VOLUME OF 76.2 ML AT A PARTICULAR TEMPERATURE AND PRESSURE, WHAT VOLUME WOULD 0.43 MOL OF ARGON HAVE UNDER THE SAME CONDITIONS?Given:n1 = 0.25 mol
n2 = 0.43 mol
V1 = 76.2 mL
V2 = ?
Equation:
V1 = V2
n1 n2
V2 = V1n2
n1
V2 = (76.2 mL)(0.43 mol)
0.25 mol
V2 = 131 mL
IDEAL GAS LAWBoyle’s LawCharles’s LawAvogadro’s
LawGay – Lussac’s
Law
Ideal Gas Equation:
V ά nT/PPV = nRt
R (gas constant)
= 0.0821 L. atm mol. K
GAS CONSTANT
PV = nRT
R = PV nT
R = (1 atm) (22.4L)
(1 mol) (273K)
R = 22.4 atm.L 273 mol.K
R = 0.0821 L.atm/ mol.K
WHAT VOLUME WILL 1.27 MOL OF HELIUM GAS OCCUPY AT STP?
Given:n= 1.27 molP = 1 atmT = 273 KR = 0.0821 L.atm mol.KV = ?Equation:
PV = nRT
V = nRT P
V =(1.27mol)(0.0821L.atm/mol.K)(273K) 1 atm
V = 28.5 L
APPLICATIONS OF IDEAL GAS LAW
Mountain climbers often carry oxygen tanks with them. The air at these higher altitudes is at lower atmospheric pressure or is ``thinner.'' This phenomenon in which pressure decreases with increasing altitude occurs in all fluids.
DALTON’S LAW OF PARTIAL PRESSURE
Partial Pressure- the pressure each gas would exert at the same temp. and at the same volume.
Ptotal = PA + PB + PC +……Pn
A CONTAINER HOLDS THREE GASES, OXGEN, CO2, AND HELIUM. THE PARTIAL PRESSURES OF THE THREE GASES ARE 2 ATM, 3 ATM AND 4 ATM RESPECTIVELY. WHAT IS THE TOTAL PRESSURE INSIDE THE CONTAINER?Given:
PA = 2 atm
PB = 3 atm
PC = 4 atm
Ptotal = ?
Equation:
Ptotal = PA + PB + PC
Ptotal = 2 atm + 3 atm+ 4 atm
Ptotal = 9 atm
IN A CLOSED SYSTEM, THE CHAMBER IS PRESSURIZED TO 1200 TORR. IF THE CHAMBER HOLDS 3 MOLES OF N2, 2 MOLES OF O2 AND 1 MOLE OF F2, WHAT IS THE PRESSURE OF EACH GAS?
P total = 3 P1+ 2P2 + 1P31200 torr = 6PP = 1200 torr/6 = 200 torr
N2 = 3 (2oo torr) = 600 torrO2 = 2 (200 torr) = 400 torrF2 = 1 (200 torr) = 200 torr 1200 torr
The mixing of gases due to molecular motion
The particles of gas spread out
-Passage of molecules of a gas from one container to another through a higher pressure;
- Particles of gas passing through a small opening
Diffusion Effusion
GRAHAM’S LAW OF EFFUSION
Thomas Graham- the rate of effusion
of gas is inversely proportional to the square root of its molar mass.
VB = √MWA
VA √MWB
HOW MUCH FASTER DOES O2 ESCAPE THROUGH A POROUS CONTAINER THAN SO2 UNDER SIMILAR CONDITION OF TEMPERATURE AND PRESSURE?
Given:
MW O2 = 32g/mol
MW SO2 = 64g/mol
√MWSO2 = V O2
√MW O2 = V SO2
V O2 = √MWSO2
V SO2 = √MW O2
V1 = √64 g/mol
V2 √32 g/mol
= 8/5.66 = 1.41 This means that O2 diffuses
1.41 times as fast as SO2
THE HEAVIER THE GAS IS, THE SLOWER THE GAS MOVES IN A GIVEN TEMPERATURE.
HCl = 36 g/mol NH3 = 17 g/mol
HCl NH3
NH3Cl
CONDENSED STATES OF
MATTER
Solids and Liquids- states in which the atoms or molecules are fairly close together and their behavior is determined (at least in part) by the attractions between them.
Some Characteristics of Gases, Liquids and Solids and the Microscopic Explanation for the Behavior
gas liquid solid
assumes the shape and volume of its container particles can move past
one another
assumes the shape of the part of the container which it occupies
particles can move/slide past one another
retains a fixed volume and shape
rigid - particles locked into place
compressible lots of free space between particles
not easily compressible little free space between
particles
not easily compressible little free space between
particles
flows easily particles can move past
one another
flows easily particles can move/slide
past one another
does not flow easily rigid - particles cannot
move/slide past one another
TYPES OF SOLIDSVitreous or
Amorphous Solids- shapeless solids; solids
that do not have definite melting points; its particles do not have an orderly arrangement; their arrangement is random similar to liquids.
CRYSTALLINE SOLIDSsolids that
have definite melting point like NaCl and sugar; they have an orderly arrangement of particles.
ALLOTROPEScrystalline solids
that exist in various forms like carbon, it can exist as diamond and graphite.
Covalent Ionic Metall ic MolecularParticles that occupy the lattice sites
Atoms Positive and Negative ions
Metal atoms Molecules
Nature of bonding
Electron Sharing
Electrostatic attraction
Electrical attraction
between the outer level
electron and the nuclei
Van der Waals forces
Properties They are hard, nonvolatile, and
have high melting point. They are good
insulators.
They are quite hard and brittle.
They have fairly high
melting points and are good
insulators.
They have variable melting
points and hardness. They
are good conductors of
electricity.
They are generally soft and have low
melting points. They are good
insulators.
Examples Diamond, carborundum,
quartz
Sodium chloride,
potassium nitrate, sodium
sulfate
Copper, iron, aluminum
Ice, dry ice, sucrose, iodine
Propert ies of Solids Based on the Type of Bonding
Process Phase Change Direction of Movement of Heat
From ToMelting (fusion) Solid Liquid Heat goes into the solid as it
melts.Freezing(Solidification) Liquid Solid Heat leaves the liquid as it
freezes.Vaporization Liquid Gas Heat goes into the liquid as it
vaporizes.Condensation Gas Liquid Heat leaves the gas as it
condenses.Sublimation Solid Gas Heat goes into the solid as it
sublimes.Deposition Gas Solid Heat leaves the gas as it
solidifies.
PHASE CHANGES- occur by either the absorption or release of energy usually in the form of heat.
Heat Movement During Phase Change